Joint for electric power cables



June 1, 1948. LENQ AL JOINT FOR ELECTRIC rowan CABLES Original FiledFeb. 23, 1940 9 mm mm vm Q 3 a a w on w R mm Q E m/// wwv// 5 (w w \vmyanmg oR/YE Y Patented June 1, 1 948 m roa ELECTRIC rowan camps JohnAlbert Leno and Noel Woodhouse, London W. 0. 2, England, alaiznors toInternational Standard Electric Corporation, New York, N. Y.

Original application February 23, 1940, Serial No. 320,378. Divided andthis application May 16,

1942, Serial No. 443,291.

March 24, 1939 v 4 Claims.

This invention relates to a joint for electric power cables and isdivided from application Serial No. 320,378, filed February 23, 1940,now abandoned.

It is an object of the present invention to provide a joint for electricpower cables that can be rapidly assembled.

The invention will be understood from the following description taken inconjunction with the accompanying drawing in which Fig. 1 shows a jointconstructed according to the invention, and Figs. 2 and 3 illustraterespective modifications of the Joint shown in Fig. 1.

Fig. 1 shows a joint made between two power cables 8, 9. The cables 8, 9comprise respectively lead sheaths i0, H, insulation l2, l3 and.conductors I 4, l5. In the preparation of the joint,

there is used a structure 5 which may be completely formed and tested inthe factory, thereby reducing the jointing time required in the field.This structure 5 comprises two condenser cones i, 2 and may be formed bywinding conductive layers 3 and insulating layers 4 on a common formeris in such a way that the two cones 3 and 4 are held together byinter-leaving layers of insulation forming an annulus 6 of insulationbetween the cones i and 2. The two cones l, 2 and the additionalinsulation 6 are wound in one operation, for example, from a single rollof paper or other insulant, prior to apphcation to the cable. Theinsulation is, therefore, preformed and may comprise single compactcylinder formed upon a metal tube, the insulation :3 being provided withmetallic conducting layers to give the condenser cone efieet.

The insulation 4, it, may comprise paper im pregnated with oil, paperimpregnated with polymerized material (e. g. paper impregnated withpolystyrene, hereinafter referred to as styrenated paper), or othersuitable insulating material. If styrenated paper he used thestyrenation may be eiiected by impregnating the condenser roll 5comprising the two condenser cones I, 2 with monomeric styrene andsubsequently eflecting polymerisation. Alternatively, pre-styrenatedpaper may be employed and adjacent layers welded together after windingby heating. This or a similar method may be employed if a sheet or filmof styrene, styrene rubber, or a blend of styrene with other polymerssuch as polyisobutylone. is used for winding the roll. It may here beemphasised that should it be desired to construct a barrier or stopjoint then polymerised material should be employed.

In Great Britain 2 cable length, the conductors it, ii are jointed by aferrule, and the roll is then slid along until it is centrally over theferrule.

The ferrule 32, 33 comprises a tubular part 34,

'35 arranged to fit over the associated conductor It, IS and a plug part35, 31 adapted to be inserted into the tubular former it of thestructure 5, which is of good conducting metal: The plug part 36, 31 ofeach ferrule 32, 33 is of spring formation as shown so that when theplug parts of the two ferrules have been inserted into the tubularformer i8 the electrical continuity of the cable is maintained throughthe former i8.

A metal joint sleeve i5 is then applied overall and plumbed to the leadsheaths I0, I! o! the cable lengths as shown at 20, 2|. The interior ofthe sleeve l9 may then be evacuated and filled with an insulatingcompound (preferably plastic and non-migratory, e. g. polystyrene or thelike) in any suitable manner. The inner diameter of the sleeve It may besubstantially equal to the outer diameter of the roll '5 and may bebonded thereto by means of styrene or the like. On the other hand whenmigratory compound is used, the sleeve 49 may be or greater internaldiameter than that of the external diameter of the roll 5, which mayalso be eccentrically disposed within the sleeve it in such a mannerthat there is an excess of filling compound at the upper side of thejoint, the outer surface of the roll 5 in such a case being preferablymetallised and. maintained at sleeve potential. by means oi a conductivespring contacting with the exterior of the roll and. the interior of thesleeve it.

The arrangement just described is illustrated in Fig. 2 where the sleeveit has an inner diame ter greater than the outer diameter of the roll 5,the resulting intervening space being filled with migratory compoundsuch as oil. A spring 1 extends between the inner surface of the sleevei8 and the outer, metallized'surface of the r0115 to provide conductivecontact between the two surfaces.

In cases in which the sleeve I9 is of greater diameter internally thanthat of the roll 5 and barrier action is required, the space between thesleeve i9 and the roll 5 may be divided into two or more compartments byone or more radial discs (e. g. of metal or insulating material) whichmay be bonded to the sleeve l9 (e. g. by polystyrene) and thecompartments may be filled with insulating material (e. g. polystyrene)or if the outer surface of the roll 5 is metallised may be filled withmetal. An insulating roll 38, 39 may be The preformed roll 5 is slidover the end of one ll provided to build up the insulation within each 3I end of the condenser cone in order to take care of the radial voltagestress concentrated at the termination of the sheath.

Fig. 3 illustrates the case in which a plurality of insulating discs 4|extend radially between the sleeve I9 and the roll 5; the annular spaces42 formed between the discs are filled with insulating material whichmaybe polystyrene. If the other surface of the roll 5 were metallized asin Fig, 2, the spaces 42 could be filled with metal and the discs 4!could likewise be of metal.

The joint may be prepared by securing the ferrules 32, 33 in positionon'the conductors l4, 15 after which the plug part of one of theferrules, e. g. the plug part 36 of the left-hand ferrule 32 in thedrawing ma be inserted into the tubular former l8 and pushed in untilthe end of the plug part 36 abuts against a partition 40 positionedwithin the tubular former I8. Then the righthand ferrule 33 is insertedinto the. tubular former I8 by suitable manipulation of the cable length9 and the tubular former 18 may be then moved slightly towards the rightin the drawing in order to take up expansion and so on. It will,therefore, be appreciated from the above that the joint may be veryexpeditiously prepared in the manner'described, the springy nature ofthe plug parts 36, 31 ensuring satisfactory contact between the plugparts 35, 31 and the former [8, so that the electrical continuity of thejoint is maintained. It will, of course, be understood that the formerl8 should be sufficiently thick to pass the current carried by the cable8,9.

It may be mentioned that while the invention has been described withspecial reference to a single core cable, a similar method may, withadvantage, be applied to a multi-core cable.

What is claimed is:

1, Connecting means for joining the abutting ends of wire cables,comprising a hollow conductive tube spaced about and from said abuttingends, and a conductive ferrule attached to each of said ends, eachferrule comprising a first gen- .erally hollow cylindrical portion of asmaller diameter than said tube, closed at its inner end and surroundingand adapted to tightly fit about the respective cable end, and a secondcylindrical portion having an outer diameter substantially equal to theinner diameter of said tube, said second cylindrical portion beinghollow and forming a projecting termination for each cable end, andconsisting of a plurality of circumferentially spaced resilient fingerspressing against the inner Wall of said conductive tube and integrallyattached at one end to the closed end of said first portion.

2. The combination according to claim 1, in which said conductive tubeis formed with a tightly fitting transverse partition intermediate itsends, forming a stop for said ferrules and preventing the passage of afluid through said joint.

3. Power cable joint comprising a tubular metal form, condenser cones,one wound about each opposite end of said form and extendinglongispective cable end, and a second cylindrical portion having anouter diameter substantially equal to the inner diameter of said tubularform, said second cylindrical portion being hollow and projecting beyondthe cable end, and consisting of a plurality of circumferentially spacedresilient metallic tongue members pressing against the inner wall ofsaid tubular form and integrally attached at One end to the closed endof said first portion.

4. Power cable joint for joining the ends of a stranded conductor, saidjoint comprising an outer metallic sleeve and an inner tubular metallicformer, a condenser roll comprising two condenser cones of which one iswound about each opposite end of said former and extends substantiallylongitudinally beyond each end of said former, two metal connectorshoused within said former for joining said stranded conductors andcomprising a pair of metal ferrules, each ferrule comprising a firstcylindrical portion surrounding and adapted to tightly fitabout therespective conductor ends, and a second cylindrical portion having anouter diameter substantially equal to the inner diameter of said former,said second cylindrical portion being hollow and projecting beyond theStranded conductor ends to be joined, said metallic sleeve being filledwith a migratory compound, and the outer surface of the condenser rollbeing metallized and connected by means of an electrically conductivespring to the interior of the cable joint sleeve.

JOHN ALBERT LENO. NOEL WOODHOUSE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

